The present invention relates to a pressure-sensitive adhesive or, more particularly, to a pressure-sensitive adhesive suitable for coating, for example, slips of paper so as to facilitate sealing with or binding of the slips by pressing.
It is a trend in recent years that the use of non-impact printers such as xerographic machines and the like is increasing more and more for printing paper slips to record information in offices. In some of the non-impact printers, a toner is used for forming a printed image by fixing the printed image of toner with heating. When a printing sheet of paper used in such a non-impact printer is provided in advance with a coating layer of a pressure-sensitive adhesive on certain areas with an object to facilitate sealing or binding the printed sheet, a trouble is sometimes encountered in printing that the pressure-sensitive adhesive is softened in the process of fixing of the toner-former printed image with heating so that parts of the printer are stained by the softened pressure-sensitive adhesive leading to a damage to the printer machine.
Besides, in a printer in which the fixing roller is coated with a silicone oil, a trouble is caused by the transfer of the silicone oil to the surface of the pressure-sensitive adhesive layer leading to a decrease in the adhesive bonding strength of the pressure-sensitive adhesive on the printing paper.
When an adhesive-coated paper sheets are stacked one on the other or a continuous-length sheet of paper coated with a pressure-sensitive adhesive is zigzag folded to facilitate storage or transportation, the adhesive-coated surfaces of the sheet or sheets sometimes causes a phenomenon of blocking to greatly disturb smooth feeding of the printing sheet or sheets to the printer.
The above mentioned problems are almost unavoidable in any types of pressure-sensitive adhesives including those based on natural rubber having good thermal stability and relatively free from the danger of adhering to the surface of the rollers and the like built in the printer even when it is somewhat softened by the heat of fixing.